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High temperature reaction of multiple eutectic-component system; The Case of solid metallic Zr and molten stainless steel-B$$_{4}$$C

墨田 岳大; 小畠 雅明; 高野 公秀; 池田 篤史

Materialia, 20, p.101197_1 - 101197_11, 2021/12

The eutectic melting, one of the fundamental phenomena in high temperature reactions involving liquid phases, is a primitive but important subject for both scientific and industrial fields associated with metallurgy. The present study aims at revealing the formation and reaction mechanisms of the multiple eutectic-component system consisting of solid metallic Zr and molten stainless steel- boron carbide (SS-B$$_{4}$$C) by combining multiple analytical methods (i.e. powder X-ray diffraction (PXRD), scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), and dynamic secondary ion mass spectrometry (D-SIMS)) with thermodynamical consideration. The results indicate that the solidified Zr-SS-B$$_{4}$$C mixture is composed of major phases of (Fe,Cr)$$_{2}$$Zr, (Fe,Cr,Ni)$$_{2}$$Zr, (Ni,Fe)Zr$$_{2}$$, ZrB$$_{2}$$, and a minor phase of ZrC. The results also reveal that the eutectic melting between solid metallic Zr and molten SS-B$$_{4}$$C can be described as the combination of diffusion kinetics and thermodynamic stability. That is, the initial formation of ZrC and ZrB$$_{2}$$ layers at the reaction interface significantly retards the diffusion of other SS-B$$_{4}$$C components (i.e. Cr, Fe, and Ni) into solid metallic Zr.


Dynamics of radiocaesium within forests in Fukushima; Results and analysis of a model inter-comparison

橋本 昌司*; 田中 拓*; 小松 雅史*; Gonze, M.-A.*; 坂下 渉*; 操上 広志; 仁科 一哉*; 太田 雅和; 大橋 伸太*; Calmon, P.*; et al.

Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11




A Modeling study on the oceanic dispersion and sedimentation of radionuclides off the coast of Fukushima

上平 雄基; 内山 雄介*; 川村 英之; 小林 卓也; 乙坂 重嘉*

Journal of Environmental Radioactivity, 238-239, p.106724_1 - 106724_16, 2021/11




Isotope shift and hyperfine structure measurements on triple resonance excitation to the autoionizing Rydberg state of atomic strontium

岩田 圭弘; 宮部 昌文; 赤岡 克昭; 若井田 育夫

Journal of Quantitative Spectroscopy & Radiative Transfer, 275, p.107882_1 - 107882_9, 2021/11



Analysis of Fukushima-Daiichi Nuclear Power Plant Unit 3 pressure data and obtained insights on accident progression behavior

佐藤 一憲

Nuclear Engineering and Design, 383, p.111426_1 - 111426_19, 2021/11

The D/W (Drywell) and S/C (Suppression Chamber) pressure data of Fukushima-Daiichi Nuclear Power Plant Unit 3 was analyzed in depth. This analysis provided valuable information related to the accident progression behavior on one hand, and gave a hint for understanding of the debris-to-coolant heat transfer when fuel debris relocated to the pedestal on the other hand. In this unit, the D/W and S/C pressure increased and decreased cyclically with a relationship, which seems to have been dependent on the composition of vapor and non-condensable gases in the S/C cover gas region. Based on this characteristic, the vapor pressure in the S/C cover gas region was evaluated for two pressure decrease cycles during and after the expected debris relocation to the pedestal respectively. This evaluation allowed an understanding that the S/C vapor pressure increased due to the heat transfer from the debris relocated to the pedestal.


Impact of extreme typhoon events on the fluvial discharge of particulate radiocesium in Fukushima Prefecture

中西 貴宏; 大山 卓也; 萩原 大樹; 佐久間 一幸

Journal of Coastal Research, 114(SI), p.310 - 314, 2021/10



Validity of the source term for the Fukushima Dai-ichi Nuclear Power Station accident estimated using local-scale atmospheric dispersion simulations to reproduce the large-scale atmospheric dispersion of $$^{137}$$Cs

門脇 正尚; 古野 朗子; 永井 晴康; 川村 英之; 寺田 宏明; 都築 克紀; El-Asaad. H.

Journal of Environmental Radioactivity, 237, p.106704_1 - 106704_18, 2021/10




Simulation study of a shield-free directional gamma-ray detector using Small-Angle Compton Scattering

北山 佳治; 寺阪 祐太; 佐藤 優樹; 鳥居 建男

Journal of Nuclear Engineering and Radiation Science, 7(4), p.042006_1 - 042006_7, 2021/10

Gamma-ray imaging is a technique to visualize the spatial distribution of radioactive materials. Recently, gamma-ray imaging has been applied to research on decommissioning of the Fukushima Daiichi Nuclear Power Station (FDNPS) accident and environmental restoration, and active research has been conducted. This study is the elemental technology study of the new gamma-ray imager GISAS (Gamma-ray Imager using Small-Angle Scattering), which is assumed to be applied to the decommissioning site of FDNPS. GISAS consists of a set of directional gamma-ray detectors that do not require a shield. In this study, we investigated the feasibility of the shield free directional gamma-ray detector by simulation. The simulation result suggests that by measuring several keV of scattered electron energy by scatterer detector, gamma rays with ultra-small angle scattering could be selected. By using Compton scattering kinematics, a shield-free detector with directivity of about 10$$^{circ}$$ could be feasible. By arranging the directional gamma-ray detectors in an array, it is expected to realize the GISAS, which is small, light, and capable of quantitative measurement.


Feasibility study of the one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding

寺阪 祐太; 渡辺 賢一*; 瓜谷 章*; 山崎 淳*; 佐藤 優樹; 鳥居 建男; 若井田 育夫

Journal of Nuclear Engineering and Radiation Science, 7(4), p.042002_1 - 042002_7, 2021/10




吉川 信治; 山路 哲史*

JAEA-Research 2021-006, 52 Pages, 2021/09




Radiocesium in Shiitake mushroom; Accumulation in living fruit bodies and leaching from dead fruit bodies

Guido-Garcia, F.; 坂本 文徳; David, K.*; 香西 直文; Grambow, B.

Chemosphere, 279, p.130511_1 - 130511_10, 2021/09

 被引用回数:0 パーセンタイル:0(Environmental Sciences)



Development of a supplementary outboard side thruster system for dynamic positioning control of autonomous surface vehicle

加藤 哲*; 川村 大和*; 田原 淳一郎*; 馬場 尚一郎*; 眞田 幸尚; 藤井 俊*

International Journal of Offshore and Polar Engineering, 31(3), p.316 - 324, 2021/09



A BWR control blade degradation observed in situ during a CLADS-MADE-02 test under Fukushima Dai-Ichi Unit 3 postulated conditions

Pshenichnikov, A.; 倉田 正輝; 永江 勇二

Journal of Nuclear Science and Technology, 58(9), p.1025 - 1037, 2021/09

 被引用回数:0 パーセンタイル:0.02(Nuclear Science & Technology)

The paper summarizes the results of the control blade degradation test CLADS-MADE-02 performed in JAEA. The test focused at the beginning phase of the accident at Fukushima Dai-Ichi (1F) Unit 3. The investigation provided important data, especially on the temperature history, exhaust gas measurement and in situ video of metallic debris formation and relocation to the colder elevations under the test scenario, which reproduced oxidizing conditions during the initial phase of the 1F Unit 3 reactor heat-up. Based on the test results, some decommissioning related conclusions concerning the formation of new B-rich phases containing Cr and Fe were made.


Cs含有微粒子はいかに生成したか?; 学際研究者の推理

日高 昭秀

日本原子力学会誌ATOMO$$Sigma$$, 63(9), p.679 - 680, 2021/09



Development of the multi-cubic $$gamma$$-ray spectrometer and its performance under intense $$^{137}$$Cs and $$^{60}$$Co radiation fields

冠城 雅晃; 島添 健次*; 加藤 昌弘*; 黒澤 忠弘*; 鎌田 圭*; Kim, K. J.*; 吉野 将生*; 庄司 育宏*; 吉川 彰*; 高橋 浩之*

Nuclear Instruments and Methods in Physics Research A, 1010, p.165544_1 - 165544_9, 2021/09

 被引用回数:0 パーセンタイル:0.03(Instruments & Instrumentation)

2011年の東京電力ホールディングス福島第一原子力発電所の事故以来、世界各地で廃止措置措置に入る原子力施設が増加している。これらの原子力施設では、放射性物質の適切な管理が要求されている。そこで、ガンマ線スペクトル測定技術は、放射性物質の重要な情報を得ることができるため、有益なツールである。さらに、放射性物質の空間情報も重要であるため、ガンマ線イメージングについて求められている。しかしながら、これらの施設には、強度放射線場が広がるため、ガンマ線スペクトル測定やガンマ線イメージングが困難になる。そのため、寸法が5mm $$times$$ 5mm $$times$$ 5mmの小さなCeBr$$_3$$シンチレーター4個で分割した$$gamma$$線スペクトロメーターを開発した。上記の4個のシンチレーターは、強度放射場に特化したマルチアノード光電子増倍管と組合わせた。私たちは、$$^{137}$$Csと$$^{60}$$Coの放射線場で照射試験を実施した。$$^{137}$$Cs照射場の線量率1375mSv/hにおいて、相対エネルギー分解能が、それぞれのチャンネルで、9.2$$pm$$0.05%, 8.0$$pm$$0.08%, 8.0$$pm$$0.03%, 9.0 $$pm$$0.04%であった。



土肥 輝美

ライケン, 21(3), p.29 - 36, 2021/09



Steam oxidation of silicon carbide at high temperatures for the application as accident tolerant fuel cladding, an overview

Pham, V. H.; 倉田 正輝; Steinbrueck, M.*

Thermo (Internet), 1(2), p.151 - 167, 2021/09

Since the nuclear accident at Fukushima Daiichi Nuclear Power Station in 2011, a considerable number of studies have been conducted to develop accident tolerant fuel (ATF) claddings for safety enhancement of light water reactors. Among many potential ATF claddings, silicon carbide is one of the most promising candidates with many superior features suitable for nuclear applications. In spite of many potential benefits of SiC cladding, there are some concerns over the oxidation/corrosion resistance of the cladding, especially at extreme temperatures (up to 2000$$^{circ}$$C) in severe accidents. However, the study of SiC steam oxidation in conventional test facilities in water vapor atmospheres at temperatures above 1600$$^{circ}$$C is very challenging. In recent years, several efforts have been made to modify existing or to develop new advanced test facilities to perform material oxidation tests in steam environments typical of severe accident conditions. In this article, the authors outline the features of SiC oxidation/corrosion at high temperatures, as well as the developments of advanced test facilities in their laboratories, and, finally, give some of the current advances in understanding based on recent data obtained from those advanced test facilities.



宮原 要

電機, (820), p.70 - 73, 2021/08



Rapid analysis of $$^{90}$$Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometry

小荒井 一真; 松枝 誠; 青木 譲; 柳澤 華代*; 寺島 元基; 藤原 健壮; 木野 康志*; 岡 壽崇; 高橋 温*; 鈴木 敏彦*; et al.

Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08

 被引用回数:0 パーセンタイル:0.02(Chemistry, Analytical)



Sewage sludge ash contaminated with radiocesium; Solidification with alkaline-reacted metakaolinite (geopolymer) and Portland cement

香西 直文; 佐藤 淳也; 大杉 武史; 下山 巖; 関根 由莉奈; 坂本 文徳; 大貫 敏彦

Journal of Hazardous Materials, 416, p.125965_1 - 125965_9, 2021/08

 被引用回数:0 パーセンタイル:0(Engineering, Environmental)

Radiocesium-bearing SSA was solidified in geopolymer (GP) and ordinary Portland cement (OPC) and the characteristics of the solidified bodies were investigated by various aspects including mechanical strength, transformation of SSA components during solidification, and radiocesium confinement ability by leaching test. After static leaching test at $$^{60}$$C, $$^{137}$$Cs was hardly leached out from the GP-solidified bodies containing SSA at 30 wt% to ultrapure water ($$<$$ 0.1%), whereas more than 30% $$^{137}$$Cs was leached from the OPC-solidified bodies containing SSA at 30 wt%. GP is far superior to OPC for solidifying radiocesium-bearing SSA.

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